1. Field of the Invention
The present invention relates to a sewing machine comprising a device for changing a set value.
2. Description of the Related Art
In a sewing machine capable of selecting stitch types and patterns, a sewing operator manually changes a thread tension and then carries out sewing according to the selected sewing type and pattern. These set values are determined based on various experiments and tests which are repeated in the development stage of the sewing machine, and are generally stored as initial set values in an ROM (Read Only Memory) incorporated in the control means of the sewing machine, and are properly read in a control circuit during a sewing work and are displayed on a display section.
However, the initial set value which is optimum in the stage of tests and experiments is not always set in an optimum state depending on an assembly condition or a variation in sewing machines which are mass-produced.
More specifically, it is necessary to properly change an assembling method and components in order to reduce a manufacturing cost and eliminate drawbacks, thereby actually mass-producing a sewing machine developed through the stage of tests and experiments. For this reason, a difference in a shape and a dimension is made between a sewing machine produced by trial in the stage of tests and experiments and a mass-produced sewing machine. Moreover, each of the components of the sewing machine to be mass-produced is generally manufactured with some errors. The sewing machines assembled by using such components make different cumulative errors from each other.
Moreover, the initial set value is stored in an unrewritable ROM. Therefore, it is impossible to rewrite the initial set value of a sewing machine which is once assembled.
In order to manufacture, in a stage of mass-production, a sewing machine set to carry out sewing on a level realized in the stage of tests and experiments, for example, it is possible to propose a method of constructing a procedure for selecting and assembling components or adjusting a shape and an assembly after the completion of the assembly such that a difference in a shape is not made between a sewing machine produced by trial and a mass-produced sewing machine when optimizing the initial set value, thereby removing the difference. Moreover, it is also possible to propose a method of fabricating an ROM storing a set value optimized for each sewing machine assembled by the mass-production and to incorporate the ROM in the sewing machine.
However, there is a problem in that a great deal of cost and man-day (time) is required for all the methods described above.
In order to solve the problem, it is an object of the invention to easily and inexpensively carry out a work for changing, into an optimum set value, a set value of a mass-produced sewing machine which is not always set in an optimum state due to an assembly condition or a variation.
In order to solve the problem, a first aspect of the invention is directed to a sewing machine capable of setting working means for sewing to have a predetermined set value by electrical means and capable of selecting plural types of stitches, comprising:
a first unrewritable storage section for storing an initial set value of the working means for each of the stitch types;
a second rewritable nonvolatile storage section for storing, as a regulated set value, the initial set value read from the first storage section;
a third rewritable storage section for storing, as a driving set value, the regulated set value read from the second storage section;
set mode selecting means for selecting an initial value changing mode for changing a part or all of the initial set values read from the first storage section and storing them as the regulated set values in the second storage section and a normal mode for changing a part or all of the regulated set values read from the second storage section and storing them as the driving set values in the third storage section; and
display means capable of displaying the regulated set value and the driving set value.
According to the first aspect of the invention, the initial set value stored in the first storage section is changed and is then stored as the regulated set value in the second rewritable nonvolatile storage means in the initial value changing mode, while the regulated set value read from the second storage section is changed and stored as the driving set value in the third storage section in the normal mode. Since the second storage section is thus provided, the initial set value which is preset can easily be set to be an optimum value corresponding to the stitch type depending on each sewing machine. Moreover, the predetermined data of the second storage section and the third storage section are displayed on the display device so that a work for changing a set value and a regulating work based on stitch data can easily be carried out. The predetermined data indicate optimized initial values and upper and lower limit values to be set in relation to a procedure for a stitch which is set to each stitch, a thread tension, a knife width and a ratio of feed to differential feed. Accordingly, it is possible to easily and inexpensively fabricate a sewing machine capable of carrying out a sewing work with a high strength and an excellent appearance.
In addition, the regulated set value stored in the second storage section can be rewritten. Therefore, the regulated set value is caused to be rewritable in the maintenance of the sewing machine so that the maintenance and management of the sewing machine can be carried out easily and inexpensively.
Moreover, a second aspect of the invention is directed to a sewing machine capable of setting working means for sewing to have a predetermined set value by electrical means and capable of selecting plural types of stitches, comprising:
a first unrewritable storage section for storing an initial set value of the working means for each of the stitch types;
a second rewritable nonvolatile storage section for storing, as a regulated set value, the initial set value read from the first storage section;
a third rewritable storage section for storing, as a driving set value, the regulated set value read from the second storage section;
initial value changing means for changing a part or all of the initial set values read from the first storage section and storing them as the regulated set values in the second storage section;
normal setting means for changing a part or all of the regulated set values read from the second storage section and storing them as the driving set values in the third storage section; and
display means capable of displaying the regulated set value and the driving set value.
According to the second aspect of the invention, the initial set value stored in the first storage section is changed and is then stored as the regulated set value in the second rewritable nonvolatile storage means by the initial value changing means, while the regulated set value read from the second storage section is changed and stored as the driving set value in the third storage section by the normal setting means. Since the second storage section is thus provided, the initial set value which is preset can easily be set to be an optimum value corresponding to the stitch type depending on each sewing machine. Moreover, the predetermined data of the second storage section and the third storage section are displayed on the display device so that a work for changing a set value and a regulating work based on stitch data can easily be carried out. In addition, the regulated set value stored in the second storage section can be rewritten. Therefore, the regulated set value is caused to be rewritable in the maintenance of the sewing machine so that the maintenance and management of the sewing machine can be carried out easily and inexpensively.
A third aspect of the invention is directed to a sewing machine capable of setting working means for sewing to have a predetermined set value by electrical means and capable of selecting plural types of stitches, comprising:
an ROM (Read Only Memory) for storing an initial set value which is previously optimized as the set value of the working means in a stage of tests;
a rewritable nonvolatile memory for storing, as a regulated set value, the initial set value read from the ROM;
an RAM (Random Access Memory) for storing, as a driving set value, the regulated set value read from the nonvolatile memory;
initial value changing means for changing a part or all of the initial set values read from the ROM and storing them as the regulated set values in the nonvolatile memory;
normal means for changing a part or all of the regulated set values read from the nonvolatile memory and storing them as the driving set values in the RAM; and
display means capable of displaying set value data in the nonvolatile memory and the RAM.
In the manufacture and maintenance of the sewing machine, consequently, the initial set value can be optimized again depending on the assembled sewing machine and can be stored as the regulated set value in the nonvolatile memory, and the regulated set value can be properly changed to be optimum when the sewing work is to be carried out by using the sewing machine, and can be stored as the driving set value in the RAM. Thus, the initial set value determined in the stage of tests and experiments can easily be optimized again depending on each of the sewing machines which are assembled by mass-production. Moreover, the set value data of the nonvolatile memory and the RAM can be displayed. Therefore, it is possible to easily carry out a work for changing a set value and a regulating work based on stitch data.